I do not understand why the developer did an update when the older version with all the features was working nicely and now the version 1.0.0 removed all these features.
The reason? he re-write it from scratch...

Imagine my GNOME or KDE or MATE desktop showing me only the terminal after an update because they re-write it from scratch... or GIMP removing all keyboards shortcut as well as the "Colors" and "Tools" menu because they re-write it from scratch? (and they re-write it from almost scratch)
In comparison it's what you did!

That's not how you should behave as a software developer... You gave features, then you remove all...

This behavior will got you only negative review which will made your extension appears far at the end in no time when searching a youtube extension, which also mean people will try others extensions instead, and once people have tested others extensions they will forget you...

Plus, the 0.2.5 version in the Version history need to be re-installed every time you open Firefox even if you select to NOT update automatically (Firefox detect after a re-start of itself, that the iridium is not the latest version and disable it)

Why i kept the 5 stars. I am still asking myself...